Process for chlorinating mineral oil



Patented Dec. 12, 1944 Leonard R. Churchill, Bayonne, N. 1., John E. Schott, New York, N. Y., and Stanley P. Waugh, Bayonne, N. J., assignors, by mesne assignments, of three-fourths to Tide Water Associated Oil Company, New York, N. 1., a corporation of Delaware No Drawing. Application January 26, 1933, Serial No. 653,664

1 Claim. (01.; 260-659) This invention relates to lubricants and the production thereof, and particularly to the provision of lubricants of greatly improved qualities which are especially adapted for satisfactory lubrication under extreme pressures. Such lubricants are of particular value in providing safe lubrication for the transmissions and rear axles of automotive equipment, especially in the lubrication of such automobile parts which operate at high unit pressures andtransmit increased power. Special purposes for these lubricants are the lubrication of automotive units having hypoid" gears and the lubrication of free wheeling" transmissions. In the lubrication of such gears, ordinary lubricants will not prevent sudden seizure between the teeth of the driving pinion and those of the ring ear, with resulting rapid disintegration of the surfaces of the teeth. Lubricants of the type set forth herein are also suitable for use as cutting oils and for operations, generally, in which extreme pressure is exerted by one metal face on another metal face.

Heretofore, extreme pressure lubricants have usually been manufactured so as to contain free or combined sulphur. We have found that certain mineral oil products containing small percentages of combined chlorine will withstand increased bearing loads without any seizure taking place and show generally improved characteristics over sulphurized oils, whether these be fatty oils, mineral oils or mixtures of these, and whether the sulphur be free or combined as addition and/or substitution products. The extreme pressure lubricants which we have developed comprise chlorinated mineral oils, or blends of chlorinated and unchlorinated mineral oils, containing upwards of 0.5% chlorine. The A. P. I. gravbecome greater, the gravity increasing substantially in direct proportion to the amount of chlorine taken up. This chlorine combines with the oil to form substitution and addition products, and hydrogen chloride gas is liberated during the reaction. The greater part of the chlorine that combines with the oil is taken up by substitution, although direct addition of chlorine on the hydrocarbon molecules may take place at points of unsaturation. Approximately 20% to 23% of chlorine can be combined readily. A convenient way of determining the amount of chlorine taken up and contained by the oil is to determine the A. P. I. gravity, since a one degree decrease in A. P. I. gravity is roughly equivalent to the addition of 1% chlorine. It is possible to continue the addition of chlorine above approximately 20% but operating difiiculties are encountered owing to the oil becoming excessively viscous and very heavy. After the chlorine has been taken up by the oil, the oil is treated to eliminate free hydrogen chlorine and dissolved chlorine. This can be accomplished by washing the chic-- rinated oil with water, or with a neutralizing agent such as a solution of sodium carbonate, followed by a washing with water. Or the removal of free hydrogen chloride and chlorine dissolved in the oil can be accomplished by blowing with dry air or other inert gas, or by a combination of these methods.

In some cases where more than 20% of chicrine has been added, it has been found that the specific gravity at room temperature of the chloities of the lubricants will range from about 10 In order to manufacture a lubricant suitable for such extreme pressures, a satisfactory method is to chlorinate the mineral oil at normal, or at elevated, temperatures by bubbling chlorine gas through the oil. Oils suitable for chlorination for the production of chlorinated lubricating oil bases of this invention are non-viscous and viscous neutral mineral oils having Saybolt viscosities ranging from approximately 60 sec. to 300 sec. at 100 F. Oils 015 higher viscosity may be used, but, in general, the process is not so satisfactory. Nevertheless, oils of relatively high viscosity may be chlorinated to obtain directly, 1. e., without blending, the final lubricating oils.

As the chlorine combines with the oil, the vis cosity and the specific gravity of the material rinated oil is greater than that of water, with the result that the water will float on the material At the same time some of the oil which has taken up less chlorine will be lower. in specific gravity than the water. Some solid sediment has been analyzed and has been found to contain as high as 58% chlorine. If the chlorination is allowed to proceed too far, it becomes difiicult and almost impossible to wash the chlorinated oil satisfactorily in order to remove the hydrogen chloride, and for this reason the chlorination is usually arrested at approximately 20% chlorine content.

In the preferred method of making our extreme pressure lubricants, a chlorinated mineral oil base, containing up to approximately 20% chlorine and having a gravity near that of water, is prepared in the manner described, and this base is then blended with an unchlorinated mineral lubricating oil to obtain a finished lubricant. It will be appreciated that the viscosity of the mineral oil with which the chlorinated base is blended depends entirely on the viscosity desired in the finished oil and naturally the amount of oil added to the base, or vice versa. is determined by the amount of chlorine desired in the finished oil and the amount of chlorine contained in the chlorinated base. For general purposes, it has been found that approximately 4% chlorine in the finished lubricant is very satisfactory, but somewhat larger amounts may be used, and with much lower perccntages of chlorine the effects are very beneficial.

Two machines have been used for testing these lubricants. In order to determine the load-carrying capacity of a lubricant, a ring 1%" in di ameter and /2" wide is fastened on a shaft, which is rotated at approximately 600-640 revolutions per minute. A block of hard steel /2" square is forced against the rotating ring under definite loads. The machine is run for approximately' five minutes, after which the load is increased by increment loading until the point of failure of the lubricating film is reached. When, or in some cases just before, the film between the ring and the block fails, as shown by a marked increase in the coefficient of friction or a sudden rapid wearing or seizure of the block and ring, the block is removed, the worn area is measured and the load in pounds per square inch is calculated. The load limit of this testing machine, as now constructed, is equivalent to approximately 52,000 pounds per square inch. In this machine, a lubricant such as we have described, containing approximately 4% chlorine, has prevented seizure under pressure of 52,000 pounds per square inch, the load limit of the machine. At what pressure failure of this lubricating film would occur in such a machine is,

therefore, not known. However, it may be stated that 52,000 pounds per square inch is considerably above the point of seizure of ordinary transmission oils, which permit seizure between about 18,000 to 28,000 pounds per square inch, and also of sulphur base transmission oils, the films of which fail between about 43,000 and 45,000 pounds per square inch in this machine, and is considerably above any pressure which would obtain in the transmissions and rear axles of the present-day automobile under normal operation.

An additional advantage of such an oil is that under extreme pressure conditions the surface of the gears will not become appreciably scored. It is in this connection, more particularly, that the other testing machine is used, a purpose of this test being to determine the efficiency of the lubrication under heavy loads, as shown by the state of the surfaces which have been lubricated under extreme pressures. In this machine, the lubricant lubricates a pin A" in diameter rotated at approximately 600 revolutions per minute between bushings, to which an increasing load is applied by increment loading until the lubricating film fails. When chlorinated mineral lubricating oils such as we have described are tested in this machine, the pressure bein increased until the film finally fails, the pin shows substantially no scoring, whereas ordinary lubricants containing sulphur, either free or combined, will show very heavy scoring of the pin when the pin is removed from the machine. If in such a machine the load is increased 1000 pounds per square inch of projected area of the bearing every ten seconds, a lubricant which is unsuitable for extreme pressure will fail when the load has reached approximately 2000 pounds.

It has been found that when the percentage of chlorine is increased from zero to 1%, the load at which the failure will occur improves rapidly, and that as the chlorine concentration is increased above 1%, the rate of increase of the load necessary to produce failure increases less rapidly. Thus, when 2% of chlorine is contained in the lubricating oil, the pin will not seize until the pressure is approximately 12,000/13,000 pounds per square inch of projected area of the bearing. The pressure at time of failure increases to approximately 14,000 pounds per square inch at 4% and above this percentage it will increase gradually. For all percentages the scoring on the pin is negligible.

In the preparation of our chlorinated mineral oils suitable for extreme pressure lubrication, it is possible to chlorinate the oil directly until approximately 4%, or higher if desired, of chlorine has been incorporated into the oil, or as has been pointed out before it is advanta ous to blend a base oil containing up to 20% or higher of chlorine with an unchlorinated mineral oil. Lubricants made by chlorination without blending, and those made by blending a chicrinated base with unchlorinated mineral oil, so that the concentration of chlorine in the finished lubricant is the same, say 4%, in both cases have comparable characteristics. If desired, lubricants such as contemplated herein may be obtained by blending a chlorinated mineral oil with another mineral oil chlorinated to the same or different degree.

If the lubricant is made by subjecting the entirety of the mineral oil that is to enter into the lubricant to chlorination until a sufficient final percentage of chlorine is incorporated in the oil, the mineral oils to be used will be those that give the desired viscosities at the degree of chlorination. Mineral oils ranging in a viscosity between approximately 60 sec. Saybolt at F. and sec. at 210 F. have been used in this way.

By making a relatively highly chlorinated mineral oil base and thereafter blending a relatively small amount of this in mineral oil not chlorinated, advantages are realized, which are that there is the least difficulty in removing the chlorin and hydrogen chloride, and that the result is accomplished, more conveniently, with comparativel small apparatus.

The following examples are illustrative of the invention.

Examples A and B are illustrative of our chlorinated mineral oil lubricating bases, to be blended with mineral lubricating oils for the production of our improved extreme pressure lubricants.

Example A The oil that is chlorinated is an overhead distillate from East Texas crude, a crude which is of a mixed base but essentially paraiimic in char acter. The physical tests of the oil before chlorination are:

Gravity A. P, I 30.1 Flash F' 340 Burn F 380 Pour "F 20/25 Viscosity at 100 F sec. Saybolt 82 Color, A. S. T. M 2

The oil is chlorinated by passing chlorine gas through it. As the chlorination progresses the temperature rises to F. After chlorinating the oil for a period of 8% hours the chlorination is stopped, and the excess chlorine together with the hydrochloric acid gas (a product of the re action) is removed for the most part by blowing a current of air through the chlorinated oil. However, in order to remove all the hydrochloric acid gas dissolved in the oil, further neutralization with an aqueous solution of lye (20 B.) is preferably used. Agitation during washing is obtained by blowing a current of air through the liquid. The washing is carried out at a temperature of 180-200 F. After thorough washing, time is allowed for the separation of the lye. The lye solution is then withdrawn. Properties and chlorine content of this chlorinated oil (lubricating oil base) are found to be as follows:

Specific gravity -4 1.014 Pour F 3/5 Viscosity at 100 F sec. Saybolt- 323 Color, A. S. T. M 3 /2 Chlorine per cent 19.08

Example B In this case, the oil taken for chlorination is a so-called red oil, an overhead distillate from an asphaltic base crude, having these properties:

Gravity -n A. P. I. 19 Pour -F -20/-l5 Flash F 3'75 Burn F 425 Viscosity at 100 F "sec. Saybolt 305 Color, A. S. T. M 5

The oil is chlorinated in the same manner as in the other example, for about 8 hours. The oil is then air blown for about half an hour, after which it is treated at 180200 F. with a solution of caustic soda (20 B.) and air blown to secure complete neutralization. The lye solution is settled out and removed. Properties and chlorine content of the lubricating oil base thus prepared are: Specific gravity 1.050 Pour F 14/15 Burn F 450 Viscosity at 100 F sec. Saybolt 1,974 Color Dark Chlorine per cent 15.1 Examples C, D, E and F are illustrative of our improved extreme pressure lubricants made by" blending the chlorinated mineral oil base with diffferent unchlorinated mineral oils. It will be sufiicient to give some lubricants made with bases similar to that of Example A, containing approximately 20% chlorine. The tests of the blending oils and of the finished extreme pressure lubricants, consisting of mixtures of the base and the blending oils in the proportions given, are shown in parallel columns.

Example C The blending oil in this example is an overhead distillate from an asphaltic base crude.

Blend 95% Blend 80% l blending blending l 203 011.5% oil 20% i chlorinated chlorinated seconds Saybolt. i 218 224 230 Viscosity at 2l0 F.. .do 52 52 Chlorine l 1 3.90

l Approximate. l

Example D This blending oil is itself a blend of the oil used as a blending oil in Example C and the oil used as a blending oil in Example E.

Blend blending oil 10% chlorinated base Blending oil Viscosity at F. d a Viscosity at 210 F do Chlorine"... pcrccnt Example E i The blending oil is a steam refined stock derived from South American crude of a mixed base which is essentially asphaltic in character.

1 Blond 00% E Blending blending oil oil 10% chlorini and hastl l Gravity A. P. l .i 18.0 10.7 rinse... F.. 54.: 10:, I lre. F 0301 570 P ouL. 20/25 1 21/25 Y lSOOSlty at 100 F econds Sayboltj 1 J, 300 Viscosity at 210 F ..do 182 167 Chlorine ..pcrcent ..l l 2 1 Approximate.

Example F The blending oil is. a residual cylinder stock obtained from Pennsylvania crude.

used as extreme pressure lubricants, without blending, or they may be blended with suitable amounts of lubricating oils to obtain lubricants having desired properties and lower percentages of chlorine.

Example G The oil chlorinated in this instance is an overhead distillate from an asphaltic base crude testing as follows:

Gravity A. P, I 23.! Flash F 385 Burn ..F 435 Pour F 26/25 Viscosity at 100 F sec. Saybolt 227 Color, A. S. T. M 2% This oil is chlorinated for a period of three hours. At first the oil darkens somewhat, and then becomes lighter in color as the chlorination progresses. After chlorination is stopped, air is blown through the mixture to remove the major part of the chemically uncombined chlorine and the dissolved hydrogen chloride gas. After air blowing, the oil is treated with a 15% sodium carbonate solution and the mixture is air blown at 180'-212" F. for a period of about thirty minutes. The sodium carbonate solution is settled out and the oil is separated. The physical properties and chlorine content oi the chlorinated oil Example H In this example the oil which is chlorinated is a sci-called bright stock, which is a residual oil obtained from Pennsylvania oil and consequently paraifinic.

The oil is chlorinated under slight pressure (equal to ten inches of water) by passing chlorine gas through the oil at a slow uniform rate. The reaction causes a disappearance of the bloom of the oil within a few minutes and a darkening of the oil, although if the chlorine is passed through in a fairly rapid stream the oil becomes bleached. A fairly large amount of heat is produced and a noticeable increase in viscosity takes place. In

this particular instance chlorination is stopped at a chlorine content of 5.85%. The chlorinated oil is washed several times with a neutral saturated salt solution and is subsequently treated while warm wtih sodium carbonate crystals. The

oil is then filtered to remove all suspended materiaL The properties of the oil before and after chlorination compare as follows:

It will be understood that the examples are given for purpose of illustration and not in limitation, and that the appended claim is intended to include all novelty inherent in the invention.

We claim:

A process for chlorinating oils to increase their lubricating efficiency which consists in passing chlorine into mineral oil at normal temperature, blowing air through the oil to remove excess chlorine and hydrochloric acid gas formed during the chlorinating treatment and treating the resulting chlorinated oil by heating with an alkali solution for a suilicient period of time to neutralize and stabilize the chlorinated oil.

LEONARD R. CHURCHILL. JOHN E. SCHOTT. STANLEY P. WAUGH. 

